Nanosecond pulsed plasma technology for endodontic biofilm disinfection Project Summary This research introduces a novel physicochemical technique utilizing non-thermal atmospheric-pressure plasmas for endodontic biofilm disinfection [and evaluates the potential clinical use of the technique for root canal treatment]. The non-equilibrium plasma, a mixture of charged particles and reactive neutral species, produces germicidal effects on microbial biofilms without heating. [The shapeable plasma plumes can penetrate into anatomically complex root canal systems, including dentinal tubules, and disinfect the teeth surfaces internally and externally.] In this research we will engineer nanosecond pulsed atmospheric-pressure gas discharge devices to generate room temperature plasma plumes with shapes and characteristics enabling microbial disinfection of teeth surfaces internally and externally. In vitro studies of plasma inactivation kinetics on a panel of pathogenic oral microbes associated with endodontic infections will be conducted. Germicidal impact factors, including the microbial supporting substratum, the initial cell concentration, and the physiological state of cells, will be evaluated. Ex vivo studies of plasma antimicrobial effects against endodontic biofilm in root canals will be followed to evaluate the clinical value of the plasma technology as a root canal disinfection tool. Both microbiological analysis and microscopic imaging will be used to assess the plasma treatment results. A collaborative research team consisting of expertise in pulse power technology, plasma science, biofilm microbiology, and dentistry has been formed to conduct this multidisciplinary research. [The intensive publicity the team has received recently reveals the urgent need for novel, effective, painless, and safe disinfection tools such as the plasma dental probe in endodontic treatment. ] [This work will primarily identify and develop a novel physicochemical technique for root canal treatment clinically. Investigation of plasma germicidal effects on endodontic biofilms will advance both atmospheric-pressure plasma science and biofilm microbiology. Research in plasma treatment of endodontic microbial biofilms in vitro and ex vivo will advance our understanding of the plasma germicidal processes, determine the feasibility of the plasma technology for root canal treatment, and eventually develop a novel plasma-based strategy for the control of endodontic biofilms. In addition, research in plasma for the control of microbial biofilms will also provide important references for plasma-based new technologies for oral cares including periodontal treatment. Nanosecond pulsed plasma technology may serve as a gateway to new clinical therapeutic strategies for the control of endodontic biofilm-mediated diseases.] PUBLIC HEALTH RELEVANCE: Nanosecond pulsed plasma technology for endodontic biofilm disinfection Relevance: The objective of this research is to identify effective therapeutic strategies for control of biofilm- mediated endodontic infection, and to investigate germicidal mechanisms and biological effects of nanosecond pulsed plasmas on endodontic microbial biofilms. Biofilms are a common cause of numerous oral infections including dental decay, pulpal, periodontal and periradicular lesions, and are implicated in the failure (at a rate of 10%) of annually ~20 million root canal treatments. Success in the proposed research will have direct impact on the control of oral biofilm-mediated diseases, and thereby will improve the oral and dental health care with technology innovation.